Expansion tank for the cooling system of an internal combustion engine

ABSTRACT

A combination tank for a cooling system of water-cool internal combustion engine includes a storage tank and an expansion tank. The storage and expansion tanks house in a common container tank, so that the storage tank and the expansion tank are disposed adjacent each other in a substantially horizontal plane and separated from one another by a substantially vertical partition wall. The storage tank has a filler opening. An overflow channel internally connects the storage tank and the extension tank. The overflow channel is situated within the partition wall and is integrally formed with and positioned at an upper part of the filler opening.

TECHNICAL FIELD

The present invention relates to a combined storage tank and expansiontank arrangement for a water-cooled internal combustion engine coolingsystem, whereby the storage tank which is provided with a filler openingand the expansion tank are housed in a common container tank made fromtwo moulded plastic parts, with the storage tank and expansion tankinternally connected via a vertically disposed overflow channel.

BACKGROUND OF THE INVENTION

The above-described cooling system with a storage tank for the coolingliquid and a separate expansion tank for the expansion of the liquidduring warming-up is used for example on heavier trucks and buses wherevery high functional safety requirements are imposed.

Where the available height is restricted, it has been usual to useseparate tanks which are mounted by brackets and connected together bymeans of tubes and tube clamps. This implies that a relatively largenumber of components have to be stored and assembled during theproduction of a vehicle. Since it is desirable to reduce the number ofassembly components, combined storage tanks and expansion tanks forminga common container tank are now becoming available. This rationalizationis most effective if the container tank is made from twoinjection-moulded plastic halves which are welded together to form afinished unit with all necessary functions integrated within the twohalves.

Such a container tank is shown in DE OS 35 33 095, whereby the storagetank and the expansion tank are connected via a centrally locatedoverflow channel. A disadvantage with this arrangement, i.e. thatleakage can arise between the two chambers, has been solved by theprovision of a double walled partition wall between the two chambers,whereby infiltration is indicated by leakage of liquid through overflowholes in the double walled cavity.

TECHNICAL PROBLEM

An object of the present invention is thus to provide a container tankfor cooling liquid with minimal installation dimensions, with which thecooling system can be tested in a more reliable manner using pressurizedair.

SOLUTION

This object is achieved according to the invention by means of theoverflow channel being integral with and connected to the filler openingof the storage tank. By means of this arrangement a hermetical test canbe easily performed after affixing a test instrument in the filleropening instead of to the filler cap. In this manner the cooling systemcan be pressure-tested with the exclusion of the expansion tank.Thereafter the connection to the expansion tank can be opened and theentire system can then be pressure-tested.

Advantageous embodiments to the invention will be apparent from thedependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention will now be described in more detail withreference to the attached drawings, in which

FIG. 1 is a side view of a container tank according to the inventionwith a partially sectioned wall,

FIG. 2 is a corresponding end view of the container tank, and

FIG. 3, 4 show in broken plan views the interior of the cover and baseof the container tank.

BEST MODE OF CARRYING OUT THE INVENTION

The container tank shown in the drawings is assembled from two tankhalves 10, 11 with the joint line 12 extending in a horizontal plane.The two halves 10, 11 are suitably made by injection-moulding of apropene plastic and are joined together by heat welding.

The container tank is provided with moulded brackets 13 for directmounting in the engine compartment of a vehicle and includes twoseparate chambers, each having an opening 14 and 15. The one chamber 16forms the storage tank for the cooling liquid in the cooling system andis connected to the not shown cooling system via a base outlet 17 andtwo breather pipes 18. The other chamber 19 forms an expansion tank forthe storage tank 16 and is connected thereto via an overflow channel 20which extends between the upper portion of the storage tank 16 and thelower portion of the expansion tank 19.

As best shown in FIGS. 1 and 2, the overflow channel 20 is in the formof a flattened pipe 22 which extends between an opening 21 in the throatof the filler opening 15 of the storage tank 16 down to an opening 23which is located below the level of the bottom of the tank in a narrowtrough compartment 24. The compartment 24 further extends upwardly intothe container tank between two side walls 25 which, together with thetube 22 and a transverse wall 26, form the partition wall between thestorage tank 16 and the expansion tank 19. Further inner longitudinaland transverse walls 27 in the storage tank 16 and the expansion tank 19serve as anti-surge walls and reinforcement.

When the container tank is functionally connected to the cooling system,the above described overflow channel will then serve as an evacuationpath for air from the storage tank to the expansion tank 19. For thispurpose the opening 14 to the expansion tank is provided with a specialcap which is not shown in the drawings but is well known to the skilledman. Such a cap serves as a back valve, i.e. it prevents reducedpressure from arising within the expansion tank 19 by admittingatmospheric air from outside via a valve passage 28. At the same timethe cap prevents air from being evacuated from the container tank exceptwhen in an extreme situation the pressure exceeds a predetermined level.

When the temperature in the cooling system rises the volume of thecooling liquid will expand which results in a compression of the air inthe expansion tank 19. This compression normally continues until thestorage tank 16 is totally emptied of air. This is possible by placingthe opening 21 to the overflow channel 20 at a high location in thethroat of the filler opening 15. With further heating from the motor,the cooling liquid and air is forced from the storage tank to theexpansion tank via the overflow channel 20.

When the temperature in the cooling system drops once again, the volumeof the cooling water will reduce. When the pressure drops the coolingliquid in the expansion tank 19 will be drawn/pushed back to the storagetank 16 by means of a siphoning effect via the overflow channel 20.Since the overflow channel 20 opens into a narrow trough at the base ofthe container tank, the quantity of cooling liquid which cannot betransferred back to the storage tank 16 will be very little. This meansthat the cooling liquid in the system is utilized to the full.

A hermetical test of the entire cooling system can easily be performedafter affixing a test instrument in the filler opening 15 instead of tothe filler cap. The test instrument is suitably so shaped that itsealingly abuts both the opening 15 and the opening 21. In this mannerthe cooling system can be pressure-tested independently of the expansiontank 19. Thereafter a connection to the expansion tank via the opening21 can be opened and the entire system can then be pressure-tested. Ifduring the first pressure testing the cooling system can withstand aconsiderably higher pressure than the maximum pressure for the expansiontank, it can be concluded that there is no leakage between the storagetank and the expansion tank. It is therefore very simple to perform afunctional test even if the container tank has become opaque due to dirtand ageing.

Although a specific embodiment to the invention has been shown in thedrawings it is to be understood that further alternatives andmodifications are possible within the scope of the claims.

I claim:
 1. A combination tank for a cooling system of a water-cooledinternal combustion engine, comprisinga storage tank and an expansiontank, said storage and expansion tanks housed in a common containertank, so that said storage tank and said expansion tank being disposedadjacent each other in a substantially horizontal plane and separatedfrom one another by a substantially vertical partition wall, saidstorage tank having a filler opening, an overflow channel internallyconnecting said storage tank and said expansion tank, wherein saidoverflow channel situated within said partition wall being integral withand positioned at an upper part of said filler opening.
 2. Thecombination tank of claim 1, wherein said filler opening issubstantially centrally located on said common container tank.
 3. Thecombination tank of claim 1, wherein said common container tank includesan upper wall, a lower wall with a trough compartment, said overflowchannel has a lower opening discharging in said trough compartment. 4.The combination tank of claim 3, wherein said lower opening of theoverflow channel opens up into a region formed between two substantiallyvertical walls extending upwardly on either side of said troughcompartment.
 5. The combination tank of claim 1, wherein said overflowchannel further comprises an upper opening, said upper opening opens upat a level above an upper wall of said common container tank.
 6. Thecombination tank of claim 1, wherein the filler opening is formed withan upper primary sealing surface and a secondary sealing surfacearranged therebelow, a pressure-testing instrument being placed againstsaid secondary sealing surface for pressure testing of the storage tankand parts of the cooling system excluding the expansion tank.
 7. Thecombination tank of claim 1, wherein said common container tank is madefrom two molded plastic parts.
 8. A combination tank for a coolingsystem of a water-cooled internal combustion engine, comprisinga storagetank and an expansion tank separated by a partition and housed in acommon container tank, said storage tank having a filler opening, anoverflow channel comprising an upper part and a lower part, saidoverflow channel internally connecting said storage tank and saidexpansion tank in such a manner that said upper part being integral withsaid filler opening and said lower part opens up into said partition;and a trough compartment situated at the bottom of said container tankand between two substantially vertical side walls forming saidpartition, said lower end of said overflow channel being connected tosaid through compartment.
 9. The combination tank of claim 8 whereinsaid container tank is made from two molded plastic parts.
 10. Thecombination tank of claim 8 wherein said filler opening is centrallylocated within said container tank.
 11. The combination tank of claim 8,wherein said filler opening is formed with an upper primary sealingsurface and a secondary sealing surface,whereby a pressure-testinginstrument is sealingly placed against said secondary sealing surface topressure test the storage tank.
 12. The combination tank of claim 11,wherein said pressure-testing instrument is adapted for pressure testingof said cooling system of the internal combustion engine with exceptionof the expansion tank.
 13. The combination of claim 8, wherein said sidewalls of the partition extend substantially upwardly from both sides ofsaid trough compartment.
 14. A combination tank for a cooling system ofa water-cooled internal combustion engine, comprisinga storage tank andan expansion tank separated by a partition and housed in a commoncontainer tank, said common tank formed with at least an upper wall,said storage tank having a filler opening, an overflow channelcomprising an upper part and a lower part, said overflow channelinternally connecting said storage tank and said expansion tank in sucha manner that said upper part being integral with said filler openingand said lower part opens up into said partition; wherein said upperpart of the overflow channel is positioned above said upper wall of thecontainer tank.